"For" as a preposition:
* Use "me" when it's the object of the preposition "for." This means "me" is receiving the action of the verb.
* Example: This gift is for me. (You are receiving the gift.)
* Use "I" when it's the subject of a verb that comes after "for."
* Example: This gift is for I to open. (You are the one who will open the gift.)
"For" in other constructions:
* "For" can also introduce a purpose or reason. In these cases, the pronoun following "for" will depend on the rest of the sentence.
* Example: I went to the store for him. (He is the reason for your trip.)
Here's a simple trick:
1. Remove the "for" and see if the pronoun makes sense.
2. If it doesn't make sense, use the other pronoun.
* Example: "This gift is me." (Incorrect)
* Example: "This gift is for me." (Correct)
Remember: If you're ever unsure, it's always better to err on the side of using "me."